Method and apparatus for casting



June 17, 1958- J. B. BRENNAN 2,838,814

METHOD AND APPARATUS FOR CASTING Filed Jan. 19, 1956 5 Sheets-Sheet lFig. 5

IN V EN TOR.

June 17, 1958 J. B. BRENNAN 2,833,814

METHOD AND APPARATUS FOR CASTING Filed Jan. 19, 1956 5 Sheets-$heet 2June 17, 1958 J. B. BRENNAN METHOD AND APPARATUS FOR CASTING 5sheets-sheets Filed Jan. 19, 1956 INVENTOR. M Q ,W

June 17, 1958 J. B. BRENNAN 2,833,814

METHOD AND APPARATUS FOR CASTING Filed Jan. 19, 1956 5 Sheets-Sheet 4 u:za

q x O 6o 5 O O O INVENTOR.

June 9 J. B. BRENNAN 2,838,814

METHOD AND APPARATUS FOR CASTING Filed Jan 19, 1956 v INVENTOR.

M Q.W-M- a F 5 Sheets-Sheet 5 United Staes This invention relates to thecontinuous casting of metal and other molten materials in strip, wire,or rod form or in the form of tubing or shapes, and this invention is acontinuation in part of my U. S. Patent application Serial No. 213,559,filed March 2, 1951, now abandoned, in turn a continuation-in-part of myapplications Serial No. 642,968, filed January 23, 1946, and Serial No.147,466, filed February 18, 1940, both now abandoned.

This invention relates, for example, to a novel method and apparatus forcasting strip metal or molten material wherein a moving cavity in theform of one or more grooves is cast full of molten material while intraversing contact with a pool of molten material situated adjacent thegrooves or cavities which are filled with molten material. Thereafter,the molten material cast in said grooves or cavities is carried, whilemolten, into a solidification zone and cooling zone by carrier molds orsurfaces and the molten material therein is solidified and subsequentlyremoved therefrom continuously.

As a feature of this invention, a differential in adhesive friction isset up by traveling molds or cavities in such a manner that movement ofthe cast material through a forming and solidification die presentslittle difiiculty in the way of die friction, and the ordinary frictionwhich is generally found in forcing cast metal through a solidificationzone and through a cooling die continuously is largely eliminated. Thus,the adherence of the cast material to the moving groove or surfaceovercomes other die friction.

This invention also refers to a method and apparatus for casting a layerof metal in bonded relationship against a moving band of highertemperature melting metal such as for example casting a layer of bronzein bonded relationship against a moving layer of cold rolled steelwherein the layer of cold rolled steel is moved with at least one faceexposed to the pool of molten metal and a layer of molten metal is castand held in shape on the moving strip and moved through while molten andsolidified thereon.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features herein- "after fullyQdescribed andparticularly pointed out in the claims, the following description andthe annexed drawings setting forth in detail certain illustrative embodi'ments of the invention, these being indicative, however, of

but a few of the various ways in which the principle of the inventionmay be employed.

In said annexed drawings: Fig. 1 is a side elevation view, partly insection, of on form of apparatus constituting the present invention;

Figs. 2 and 3 are cross-section views taken substantially along thelines 22 and 3-3, Fig. 1;

Fig. 4 is a cross-section view of another embodiment of this invention;

tent O Fig. 5 is a cross-section view taken along the line 55, Fig. 4;

Fig. 6 is a side elevation view, partly in section, showing an apparatussimilar to that of Fig. 1;

Fig. 7 is a partial section view of apparatus for forming compositemetal strip;

Fig. 8 is a partial section of yet another form of casting apparatus;and

Figs. 9, 10, and 11 are horizontal section views of molds or dies whichmay be employed in the Fig. 8 apparatus.

Referring to the drawings herewith, Fig. 1 is illustrative of anapparatus suitable for carrying out the purpose of this inventionwherein 1 represents a pool of molten metal and 2 represents a ceramiccrucible containing a pool of molten metal, 3 represents an inductionheating coil for heating the metal in the ceramic crucible 2.

Below the ceramic crucible 2 containing the molten metal 1 and incooperative relationship therewith is the cooling die 4 having acoolant, such as cold water, circulating therethrough and which is incontact with the molten metal which has been previously formed into astrip on the face of the wheel 5 which is of ceramic material and whichrotates counterclockwise guided by and driven by the rollers 7 and 7a.

A guide shoe'of graphite 8 is situated against the face of the'rotatingceramic wheel 5 and spaced therefrom, said shoe 8 having one or moreopenings 8a therein for feeding the molten metal from the pool of moltenmetal against the face of the rotating wheel 5 as it rotatescounterclockwise past the openings 8a. The face of this wheel 5 may begrooved or have cavities therein and may even carry cored memberstherein.

In any case, a cavity is presented by the face of the wheel 5 as itpasses the openings 8a leading from the molt n metal pool 1 so that alayer or other form of metal is fed thereon and formed and is carrieddownward through the solidifying die 4, for example a solid strip 6.This metal strip 6 is then carried around substantially all the way overthe outer face of the rotating ceramic wheel 5 inside the rollers 7 insuch a way that there is no slippage between the cast strip 6 and theface of the wheel 5 on which it rests.

An advantage is gained by carrying this strip 6 almost all the wayaround the outer face of the wheel 5 due to the fact that the cast metalstrip 6 tends to cling to the wheel 5 due to shrinkage so that the caststrip 6 moves in exact synchronism with the wheel 5 and withoutslippage. This is partly due to the fact that a certain shrinking actionoccurs in the cast strip 6 which causes it to cling to the outer surfaceof the wheel 5.

In addition to this, the pressure of the rollers 7 on the outside of thecast metal tends to keep it in place with reference to the wheel 5. Thetension rollers 10 pick up the cast strip 6 after it has passedsubstantially around the wheel 5 and is stripped therefrom and may beused for leveling and sizing and smoothing as well as for producingtension on the strip 6 which tension can be used to cause the wheel 5 torotate in timed relation with the rollers 10 which in this case wouldgovern the speed of rotation of the wheel 5 as well as the speed ofcasting the strip 6.

A windup reel 13 picks up the cast strip 6 after it passes through therollers 10 and coils the cast strip or wire or rod suitably for furtheruse or process.

Fig. 2 represents a section of Fig. 1 taken on the line 2-2, the wheel 5having a peripheral groove therein to form a cast metal strip 6.

Fig. 3 represents an alternative cross-section taken on the line 3-3 ofFig. 1 wherein the shoe 8A and wheel 5A 3 are formed with complementarygrooves to cast wires or rods 6A.

Fig. 4 represents an alternative method and apparatus for producingstrip metal according to the teachings of the invention. Referencenumber 1 again represents a pool of molten metal, 2B represents acrucible heated by high frequency coils 3B, for example. A coiling die4B situated below the crucible 23 adjacent to the guide tube 83- havingperforations 12 therein extends downward through the pool of moltenmetal 1 and an adjoining section of the guide tube 83' then down throughthe pool of molten metal in fixed relationship and a chain 5B, ofceramic material is drawn down through the cavity to form a casting 6Bbetween the sections 88 and 8B.

The ceramic chain 513 fits closely against section 8B and in spacedrelation to the inner face of the section 8B so that a fixed spacingexists between the face of the ceramic chain 5B and is presented to themolten metal pool entrances 12. The molten metal flows into theentrances 12 and along the face of the chain 53 and is carried downthrough the solidification zone 4'.

The joints between the links of chain 5B tend to present a somewhatirregular cavity surface to the molten metal which enters through theopenings 12, and the fins of metal entering the joints assist incarrying the molten metal downward. After the molten metal 1 has beensolidified in the face of the chain 5B, it is easily carried along bythe chain and out of and through the solidification die 43 due to thegreater adherence to the somewhat irregular jointed face of the chain 5Bwith reference to the smooth inner face of the section 83. The wheels1013 guide and drive the chain 5B.

Fig. 5 represents a section view taken on the lines 55 of Fig. 4 whereinthe crucible 2B filled with molten metal 1 and surrounded by heatingcoils 3B show the openings 12 which lead from the pool of molten metal 1to make the casting 6B on the face of the chain 5B. The backing-up block8B guides the chain 53. The other sections 88 of the guide frame are forguiding the chain 5B so that a uniform casting 6B is formed on the faceof the chain 5B as it passes downward through the molten metal pool 1.

Fig. 6 illustrates a variation in construction and method of apparatussuitable for use in carrying out the purposes of this invention whereinthe molten metal pool 1 is contained in the crucible 2 which has one ormore openings 8a leading through a spacing block or spacing die 8 inspaced facial relationship with the rotating metal or ceramic wheel 5Cwhich is rotated counterclockwise by means of the belt 100 which ridesthereon and thereover.

The ceramic block wheel 5C has a groove in the face thereof similar tothat shown with reference to the grooves in Fig. l as illustrated inFig. 2 above. This groove is filled with molten metal as it passes bythe openings 8a and the molten metal is cast into and carried in thisgroove by the wheel 5C down through the solidification zone 4 andemerges as the cast strip 6 in the groove on the outer face of therotating wheel 5C. Inasmuch as there is a belt C passing around thewheel 5C and over the cast strip 6 thereon, this belt 10C keeps the cast'metal strip 6 in place on the outer groove or grooves on the wheel 50and tends to keep it from slipping and tends to keep it in timedrelation governed by the speed of the belt or chain 10C. The strip 6 iswound up and coiled on the winding reel 13.

A principal feature illustrated in Fig. 6 is that timed guiding in theform of a belt or chain, which may also be grooved or cavitied, tends tokeep the apparatus in motion without slipping, by a simple means.

Fig. 7 illustrates a type of apparatus and method whereby a casting,bronze for example, can be continuously applied to a steel strip andbonded thereto. Again in Fig. 7, we illustrate a pool of molten metal 1which metal 1.

has openings 8a in the crucible 2D leading to a cavity formed by the dieshoe 8D in spaced relation to the wheel 5D having a strip of metal 6Dheld close thereto by roller 10D, which moves counterclockwise.

Said wheel 5D, having its covered face presented to the pool of moltenmetal with a strip of steel 6D fed under roller 10D against the outerface of the wheel 5D, and moving in synchronism therewith so that itfits snugly thereon, is moved down inside the perforate die shoe 3D sothat the metal flows through the openings 8a against the outer surfaceonly of the strip 6D which strip became heated to at least the meltingpoint of molten metal 1 by high frequency coils 3D as the metal passesdown through the magnetic field of the high frequency coil 3D.

The molten metal 1 is deposited on the exposed face only of the steelstrip 6D as it is carried downward on the wheel 5D and through thecooling zone 4D so that the cast metal is solidified and bonded to metalstrip 6D and emerges as a lamination 6D on the exterior face of thesteel strip 6D. The wheel 5]) may be driven by rollers 10D 'on theoutside of the lamination 6D cast on the steel strip 6D for example,rollers 19D may be used to produce a driving tension synchronously withroller 10D to drive the wheel 5D, alternatively it may also be used todensify and improve the uniform gauge of cast lamination strip 6D.

The windup reel 13 is used to wind up the finished lamination, and thefeed reel 13D is used to supply the steel strip 6D to themolten-metal-forming die 8D under the roller 10D, which roller 10D holdsthe strip 6D closely in timed relation with the wheel motion so that nobuckling occurs when the steel strip 6D passes through the highfrequency coil 3D in contact with the molten Rollers 10D and 10D andwheel 5D are synchronized.

Fig. 8 illustrates an alternative form of apparatus wherein a ceramicchain SE is driven by the toothed wheel 10E and the ceramic chain 5E hasa deep groove at least in one face thereof or has multiple grooves inone face thereof. These multiple grooves or single grooves are moved inclose relationship to the guide 8E with the grooves open to the moltenmetal 1. The guide 8E may be preferably exactly fitted up against theopening in the groove and the ceramic members of the chain 5E as theyare carried downward in contact with the guide 8E.

The straight section of the chain 5E after it has left the wheel 10E canbe very accurately aligned. Little or no metal will flow between thejoints of the sections of the chain 5 when they are moved in straightand parallel alignment.

As the heated chain 5E passes downward, the groove therein being exposedto the pool of molten metal is filled with molten metal, and this iscarried downward through and in contact with the solidification zone 4E,and when it emerges therefrom the cast metal 6E in the groove issolidified. The strip metal 6E can then be removed from the grooves inthe chain 5E and rolled, heat-treated, or machined to suit the purposefor which it was made.

Fig. 9 illustrates a chain 5E having multiple grooves for forming stripcastings 6E therein having multiple section guide blocks 8E and 8Etherearound. Chain such as 5E, Fig. 9, will permit parting after itpasses through the guide blocks 8E and assist in the removal of the castmetal strips 6E from between the multiple members of the chain 5E.

Fig. 10 illustrates the chain 5F having a flat face and being guided byguide block 8F and having a fiat strip of cast metal 6F against its faceof chain 5F and interior groove of guide block 8F.

Fig. 11 is a broken-away section of the chain 5H being guided throughthe outer peripheral edge of the crucible 2H and having a guide grooveestablished therein by the blocks 8H. The molten metal 1 flows into thecavity in the chain 5H which will permit easy removal of the cast metal6H. The cooling zone is not shown in Fig. 11 because it is thought thatit is easily understood how this can be carried into practice. In Fig.11, the guide blocks 8H are made up of three pieces and serve toaccurately guide the chain 5H so as to present an accurate cavity grooveto the pool of molten metal.

Synthesized mica may be cast from its constitutents and crystallized insheet, bar, or tube form, using the apparatus and principles of thisinvention.

It is necessary, under these conditions, that the rate of withdrawalfrom the enclosing die, such as is used in Fig. 11 for example, besomewhat slower than the crystal growth.

The graphite crucible 2H is charged with a mixture of the followingingredients:

Percent by weight SiO 35-39 (Al, Fe, Cr, V) O 11-12 (Mg, Fe, Mn, Zn)O29-35 (Na, KhSiF 11-13 (Na, K)F 6-7 or another mixture, using the purestcomponents, may be:

Percent A1 11.6 MgO 32.6 SiO (diatomite); 30.7 K SiF 25.1

can be used to charge the graphite crucible 2H, and such charge ismelted therein or may be charged molten therein.

Initial temperature would have to be approximately 1450 C. after'beingmaintained for a time like this, the charge can-be slowly cast into thecavity of the mold H such as shown in Fig. 11, so that the filled moldand its contents are lowered and cooled until the solidification pointof 1320 C. is reached. Cooling must be kept within the crystallizationvelocity of the mica which is about 2 mm. per minute. This would be therate of withdrawal, the rate of the movement of the mold on chain 5H,Fig. 11. I

By way of specific example, apparatus of the type disclosed in Fig. 1has been employed to continuously cast metal strip 6 of 4-44 bronze andof size A x 1%" at the rate of 18 in./min. In this case, the wheel 5 wasof ceramic material, specifically silicon carbide lava, having anoutside diameter of 5 inches, an inside diameter of 4 inches, and wasformed with a peripheral groove of 1% inch width and ,4 inch depth. Thecrucible 2 was made of silicon carbide lava and was form-ed with anarcuate passage of 2x 5 inch radial cross-section to slidingly embracethe wheel 5, a graphite shoe 8 of about 7 inch length being engaged withthe peripheral surface of the wheel 5.

The induction heating coil 3 was operated at a frequency of 9600cycles/sec. and energy of 30 kva. and was operative to keep the metal inthe crucible 2 and in the die passage for a distance of about 2 inchesbelow the feed opening 8a at a temperature of about 1950 F. The coolingdie 4 was made of copper and water was circulated therethrough at a rateso that the cast strip 6 emerged from the lower end thereof at atemperature of about 700 F. and at the lineal speed of 18 in./min. asaforesaid.

Because the wheel 5 was made of poor conducting ceramic material, thatis, lava and carborundum, the frequency field heats the metal directly,rather than by conduction from the die walls, whereby the heating energyis not wasted in first heating the wheel 5to a temperature exceeding themelting point of the metal in the forming zone and then subsequentlycooling the wheel to a temperature less than the freezing temperature ofthe metal in the cooling die 4. Volcanic lava contains pumice which is65-75% silica and 9-20% alumina, the electrical resistivity of silicabeing about 77,500 ohms per centimeter cubed.

In the instant example, the operating temperature of the wheel 5 isabout 1000 to 1200 F. opposite shoe 8 and about 700 F. inside thecooling die 4.

The shoe 8 may be made of the same poor conducting ceramic material asthe wheel 5, but it has been found preferable to use graphite(electrical resistivity of only about .0014 ohm per centimeter cubed) aspreviously stated because it makes a smooth iron, it keeps one surfaceof the casting labile and lubricated, and it keeps the casting surfaceslick due to low friction.

Similar operating conditions apply to the Figs. 4, 6,

and 8 apparatuses. Now, with reference to forming composite metal stripas in Fig. 7, the Fig. 7 apparatus has been used to form composite stripmetal continuously at the rate of 18 in./min. As an example, a .040 x 1%steel strip was run around the 1% x 4 peripheral groove of the 5 inchoutside diameter ceramic wheel SD of A1 0 and a .022 x 1%" layer of 4-44bronze was cast against the exposed exterior face of the steel strip. IThe induction heating coil (9600 cycles, 20 kva.) was operative tomaintain the bronze at a temperature of 2250 F. in the casting andforming zone (below opening 8a) and to heat the steel strip to about1950 F. whereby the bronze welds to the steel. The cooling die trowelssmooth the surface of the bronze layer and the latter solidifies duringthe course of its movement through the cooling die 4D and issuestherefrom at a temperature of about 700 F.

Again, as in Fig. 1, the steel strip and the bronze are inductivelyheated to the proper temperatures without alternately heating andcooling the wheel 5 as would otherwise be required if flame, resistance,or other heating means were employed.

When casting is done against a rotating wheel 5, the

extensive arc of contact of the metal therewith results in shrinkadherence to ensure carrying of the metal by the wheel through thecasting and cooling zones. The arc of contact preferably should be inexcess of one-third of the wheel circumference.

Further noteworthy features of this invention are that castings can becontinuously made as long as metal is supplied to the pot or crucible 2;that variable head feed may be utilized if desired; that metal stripscomposed of metals having melting points in excess of 500 C. may besatisfactorily and continuously cast; that the casting zone of the dieis less receptive to inductive heating than the metal being cast wherebythe induction heating field acts principally on the metal being cast;and that the casting produced has a slick, ironed surface which isuninterrupted on at least one face and is of such flexibility as to becoilable and windable upon itself after being produced.

Another point which should be emphasized is that, although there is apot of molten metal within an induction heating coil, which pot isspaced about A inch from the coil, not enough heat is radiated from thepot to evaporate atmospheric moisture which condenses on thewater-cooled induction coil. Thus, there is considerable economy ofenergy and lack of radiation losses.

It is to be noted that the moving die member has a greater area thereofin contact with the casting metal or the base strip, .s the case may be,and that said moving member is less affected by the induction heatingfield because of its continuous movement past said field and because ofits being made of ceramic material as indicated.

Stated in another way, the heat is cumulative in the stationary memberof the die, but the moving wheel or moving member has a differentportion thereof exposed to the influence of the induction heating fieldas it moves with respect to said field. Preferably, a major portion ofthe cooling of the cast strip metal or of the lamination is through themoving die member.

It is to be further noted that the stationary member of the die may beat least partly cooled by the heat extracted from and through the movingmember or wheel.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

I therefore particularly point out and distinctly claim as my invention:7

1. The method of continuously casting metal strip and the like whichcomprises the steps of continuously feeding molten metal into the upperend of a downwardly extending, open-ended die passage of which one wallis movable downwardly and is of ceramic material having a relatively lowelectrical conductivity comparable with that of silicon carbide lava andof which the opposite wall is stationary and is of ceramic materialhaving a relatively high electrical conductivity comparable with that ofgraphite; continuously moving such die wall to carry the metaldownwardly therewith through the die passage; passing the downwardlymoving body of molten metal in the die passage through an inductionheating field which is effective to inductively heat the metal itself toa temperature exceeding its melting point without such die wallattaining that temperature from the effects of the induction heatingfield it is fed into the die passage and which is effective toinductively heat such stationary die wall so as to keep the metal incontact therewith labile and lubricated and to keep its surface slickdue to low friction and as it flows downwardly through the die passagewhereby the metal is formed, while molten, to the cross-section shape ofthe die passage; passing the formed body of molten metal through anadjacent cooled portion of the die passage to solidify the metal in itsthus hot-formed shape before it emerges from the lower end of the diepassage by' extraction of heat therefrom by the movable wall of the diepassage and by an opposite wall of the die passage; and continuouslyremoving the solidified metal from the movable wall after the metal hasemerged beyond the lower end of the die passage.

2. Apparatus for continously casting metal strip and the like whichcomprises a downwardly extending, openended die of which one wall ismovable downwardly and is of ceramic material having a relatively lowelectrical conductivity comparable with that of silicon carbide lava andof which the opposite wall is stationary and is of ceramic materialhaving a relatively high electrical conductivity comparable with that ofgraphite; means for continuously moving such die wall to carrydownwardly molten metal fed into the upper end portion of said die;induction heating means around said die efiective to inductively heatthe metal itself to a temperature exceeding its melting point withoutsuch die wall attaining that temperature from the efiects of theinduction heating field as it is fed into the die passage and effectiveto inductively heat such stationary die wall so as to keep the metal incontact therewith labile and lubrication and to keep its surface slickdue to low friction and as it flows downwardly through the die passagewhereby the metal is formed, while molten, to the cross-section shape ofthe die passage; and cooling means around a downwardly adjacent portionof said die effective to solidify the metal in its thus hot-formed shapebefore it emerges from the lower end of the die passage by extraction ofheat therefrom by the movable wall of the die passage and by an oppositewall of the die passage; the solidified metal being removed from themovable die wall after the metal has emerged beyond the lower end of thedie passage.

References Cited in the file of this patent UNITED STATES PATENTS359,349 Daniels Mar. 15, 1887 368,817 Daniels Aug. 23, 1887 437,509Pielsticker Sept. 30, 1890 1,651,678 Davis Dec. 6, 1927 2,092,284McCarroll et al Sept. 7, 1937 2,139,215 Wasson Dec. 6, 1938 2,206,930Webster July 9, 1940 2,242,350 Eldred May 20, 1941 FOREIGN PATENTS734,890 Germany Apr. 30, 1943

